The invention relates to a hard magnetic material which comprises at least a rare earth metal and a transition metal chosen from the group consisting of iron and cobalt.
Known materials of this type are, for example, materials which comprise a rare earth metal, iron or a mixture of iron and cobalt and boron. These materials comprise a fine crystalline phase of a tetragonal crystal structure of substantially the composition (RE).sub.2 (Fe,Co).sub.14 B. A known compound of this type is Nd.sub.2 Fe.sub.14 B. This compound has particularly good magnetic properties.
However, it has been found in practice that poisonous boron compounds can easily be formed in the manufacture of the known boron-containing materials.